Is there a way to prohibit changing `latinit` properties after they've been initialized? Something i...

# announcements

[Karlo Lozovina]

Is there a way to prohibit changing latinit properties after they've been initialized? Something in the stdlib maybe?

[ephemient]

can't think of anything in stdlib but building your own is straightforward.

class LateInitOnce<T : Any> {
    private lateinit var value: T
    operator fun getValue(thisRef: Any?, property: KProperty<*>): T = value
    operator fun setValue(thisRef: Any?, property: KProperty<*>, value: T) {
        require(!this::value.isInitialized) { "LateInitOnce property has already been initialized" }
        this.value = value
    }
}

val once by LateInitOnce<String>()
once // throws UninitializedPropertyAccessException
once = "first" // ok
once // ok
once = "second" // throws IllegalStateException

[nfrankel]

i’d suggest a delegated property
https://stackoverflow.com/questions/48443167/kotlin-lateinit-to-val-or-alternatively-a-var-that-can-set-once

[nfrankel]

@ephemient you beat me to it

[ephemient]

I didn't look at SO and I like my code better than what's on there anyway :D

[nfrankel]

i didn’t look at SO
i looked at google and found an answer i accepted

[Karlo Lozovina]

Thanks both of you, will go this route... I was thinking if there was anything in the stdlib, such as lazy or observable properties...